Metal heat exchanger tank and method of forming same

ABSTRACT

A heat exchanger ( 10 ), such as a radiator, includes a metal tank ( 12 ) having a foot ( 28 ) that is integrally formed therewith. The heat exchanger ( 10 ) also includes a header ( 14 ) having a plurality of crimping tabs ( 44 ) extending therefrom. The integral foot ( 28 ) of the metal tank ( 12 ) has an upper surface ( 30 ) and a lower surface ( 32 ) with the lower surface ( 32 ) intended to rest within an internal channel ( 46 ) formed in the header ( 14 ). The crimping tabs ( 44 ) are folded around the footer ( 28 ) so as to lie above and generally parallel to the footer upper surface ( 30 ) in order to retain the metal tank ( 12 ) in proper alignment with the header ( 14 ). After the metal tank ( 12 ) and the header ( 14 ) are physically assembled, they are sealed to form a leak-free joint.

TECHNICAL FIELD

[0001] The present invention relates generally to a metal end tankdesign for a heat exchanger and, more particularly, to a metal end tankfor a heat exchanger having an integral foot formed around the perimeterof the tank to allow for easy assembling of the tank to an associatedheader.

BACKGROUND ART

[0002] Automobile radiators have typically been manufactured from copperand brass with brass being utilized for the headers, tubes, tanks, andconnectors, and copper being utilized for the fins. Further, eithersteel or brass was utilized for the side channels and brackets. Thesecomponents were typically joined through soldering. As is known,soldering is largely labor intensive, and allows for easy re-working ofjoints, as solder can be used to fill large gaps which werecharacteristic of poor manufacturing tolerances. The typicaltank-to-header joint included a tank with a straight wall mated to thestraight inner wall of the header. With this configuration, a very thinchannel would typically remain in the header into which the tank wallwould slide. This channel would then be flooded with solder to fill thesurrounding joint area until there were no more leaks. These copper andbrass radiators were extremely heavy and not very durable.

[0003] Subsequently, brazed aluminum radiators were proposed in aneffort to reduce the cost and weight of the prior copper and brassradiators. While the aluminum radiators were lighter, had comparableheat transfer properties, and increased life, there were technicalconcerns relating to cleaning, brazing and corrosion by eitherenvironmental conditions or by the coolant itself. These issues weresubsequently overcome and robust, low-cost, manufacturing processes forbrazing aluminum automobile heat exchangers were developed. However,other problems still existed with these processes, including theinability to effectively draw aluminum to make the same style tanks ashas been done previously with brass. Moreover, it was also determinedthat the attainable manufacturing tolerances were nowhere near what wasnecessary to consistently braze, leak-free joints. Thus, themanufacturing processes or tolerances, which were satisfactory forcopper and brass radiator components, were not sufficient to meet thedemands of the aluminum brazing process. Thus, these designs wereunacceptable due to the inability to properly draw deep-walled aluminumtanks suitable for automobile radiators, as well as the inability toachieve leak-free brazing.

[0004] As an alternative, plastic injection molded tanks were developed.These plastic tanks utilized an intermediary gasket, or seal, and aheader crimping mechanism to provide the joining and sealing force. Theinjection molded tanks also provided the ability to mold-in any neededconnectors, filler necks, and brackets, which alleviated the need tofabricate those pieces individually. The plastic end tanks were,however, prone to cracking, especially at the hose connector locationsand particularly under extreme temperature conditions or in applicationsover rough terrain where the heat exchanger is subjected to continuousharsh vibratory conditions. The susceptibility to cracking also posedanother manufacturing problem, in that the crimping operation was notvery tolerant to variation, so the crimping operation itself couldresult in many cracked tanks.

[0005] Efforts to solve the drawing problems present with aluminumtanks, as discussed above, were proposed. In so doing, these designsattempted to minimize joint clearances by using a straight-wall tankdesign similar to that which had been used in copper and brassradiators. While some of these designs could be successfully brazed, itwas determined that the aluminum headers would often fail prematurelydue to fracturing at the pinch point of the very thin channel.

[0006] Presently, the reliable method of achieving a successful jointand making a good radiator is to cut the tabs off of a tabbed header andto weld the tank to the header. With a flat spot normally reserved for agasket and a more suitable radius, the plastic tank radiator headerstypically do not fail, even after having an aluminum tank weldedthereto. This method is still disadvantageous as it is expensive,suffers from irregularities, and requires labor intensive hand weldingof tanks.

[0007] Recently, there have been attempts to stray from the traditionalshape of the radiator tank in an effort to provide a more efficientprocess. Some of these attempts included utilizing single or multipleextrusions which, when joined, together serve as the tank and theheader. These attempts produced a trade-off in terms of clearance issuesin the vehicle, ease of locating mounting brackets, and reduced tankcapacity. Moreover, the extrusion process tended to be very expensiveand very limiting.

[0008] Thus, there remains a need for a low cost radiator design that iseasy to manufacture and provides the requisite strength and sealability.

SUMMARY OF THE INVENTION

[0009] It is therefore an object of the present invention to provide ametal end tank for a heat exchanger that provides interchangeabilitywith both current design headers and newer generation design headers.

[0010] It is a further object of the present invention to provide amethod of attaching a metal end tank to a heat exchanger which assuresproper contact and alignment of the components prior to sealing, such asthrough brazing.

[0011] It is another object of the present invention to provide a metalend tank for a heat exchanger that can quickly and efficiently beintegrated with current manufacturing processes in a rapid andcost-effective manner.

[0012] It is a still another object of the present invention to providea metal end tank for a heat exchanger that provides superiorrecyclability attributes, superior crash worthiness, and superiordurability.

[0013] It is yet a further object of the present invention to provide ametal end tank for a heat exchanger that yields increased product lifeover current products without adding significant additional weight.

[0014] In accordance with the above and other objects of the presentinvention, a metal end tank heat exchanger is provided. The heatexchanger includes a metal tank having a foot that is integrally formedtherewith. The heat exchanger also includes a header having a pluralityof crimping tabs extending therefrom. The integral foot of the metaltank is intended to rest within an internal channel in the header whenassembled. The crimping tabs are intended to be folded to retain themetal tank in position with respect to the header. After the metal tankand the header are physically assembled, they are sealed to form aleak-free joint.

[0015] Additional features and advantages of the present invention willbecome apparent to one of skill in the art upon consideration of thefollowing detailed description of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a top view of a heat exchanger in accordance with apreferred embodiment of the present invention;

[0017]FIG. 2 is a front view of the heat exchanger of FIG. 1;

[0018]FIG. 3 is an exploded front view of a heat exchanger in accordancewith a preferred embodiment of the present invention;

[0019]FIG. 4 is an exploded frontal view of a heat exchanger inaccordance with another embodiment of the present invention;

[0020]FIG. 5 is an exploded side view of the heat exchanger of FIG. 4;

[0021]FIG. 6 is an enlarged view illustrating the crimping of the headerto the footer of the tank in accordance with a preferred embodiment ofthe present invention; and

[0022]FIG. 7 is an enlarged view illustrating the crimping of the headerto the footer of the tank in accordance with another preferredembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

[0023] Referring now to FIGS. 1 through 5, which illustrate a heatexchanger in accordance with a preferred embodiment of the presentinvention. The preferred heat exchanger can be utilized in a variety ofapplications, including automotive radiators, heater cores, air coolers,and other automotive and non-automotive applications.

[0024] The heat exchanger 10 includes a metal tank 12 and a header 14,which is physically retained on the metal tank 12, as discussed in moredetail below. The tank 12 is preferably a stamped aluminum part that isformed during a multiple stage stamping operation. However, the tank mayalternatively be cast, custom fabricated or extruded. The process bywhich the metal tank is formed is not critical. The tank may also beformed of a variety of materials, including, steel, stainless steel,brass, aluminum, as well as various combinations of the above and othermaterials. The header 14 is also preferably an aluminum part, however,the header may also be made from a variety of materials, including thesame materials described above in connection with the tank 12.

[0025] As shown, the metal tank 12 has a top surface 16, a bottomsurface 18, a front surface 20, a rear surface 22, and a pair ofopposing side surfaces 24, 26. The front surface 20, the rear surface22, and the pair of opposing side surfaces 24, 26 are preferablygenerally planar and extend upward in a generally perpendiculardirection from the bottom surface 18 to form a deep-walled tank. Themetal tank 12 also has an outwardly extending foot 28 that is integrallyformed therewith. The foot 28 preferably extends around the entireperiphery of the tank 12 and preferably extends generally perpendicularto the tank outer surface. It should be understood that instead of asingle foot, a plurality of individual feet could extend around and bespaced about the periphery of the tank 12. Moreover, the foot 28 couldalso extend outward and slightly upward, downward, or be curved. Thetank foot 28 has an upper surface 30 and a lower surface 32.

[0026] The header 14 has bottom surface 34, a front surface 36, a rearsurface 38, and a pair of opposing side surfaces 40, 42. The frontsurface 36, the rear surface 38, and the pair of opposing side surfaces40, 42 each extend upwardly in a generally perpendicular direction fromthe bottom surface 34. The front surface 36, the rear surface 38, andthe pair of opposing side surfaces, 40, 42 each have a plurality orcrimping tabs 44 formed thereon. The crimping tabs 44 allow the-header14 to be fixedly secured to the foot 28 of the metal tank 12. Thecrimping tabs 44 are preferably formed on the front surface 36, the rearsurface 38, and the pair of opposing side surfaces 40, 42 of the header14. The header 14 preferably also has an internal channel 46 formed inits bottom surface 34 thereof, such that an island 48 is formed in thecenter thereof. It should be understood that the header 14 preferablyhas an island 48 formed therein, however headers 14 without islands mayalso be utilized.

[0027] The internal channel 46 is intended to receive the foot 28 of themetal tank 12 therein when assembled. As shown in FIGS. 4 and 5, asealant such as a gasket 50 can be located between the lower surface 32of the tank foot 28 and the internal channel 46 of the header 14.Alternatively, another sealant such as an adhesive, brazing pre-form, orother filler may be utilized. Further, a spacer 52 (FIG. 7) may also bepositioned between the crimping tab 44 and the upper surface 30 of thetank foot 28, when assembled.

[0028] The preferred heat exchanger 10 allows for the use of a currentheader design with or without a spacer or insert or for the use of a newgeneration header design with or without the use of additional inserts.As shown in FIG. 6, one method for attaching the metal tank 12 to theheader 14 is shown. In this embodiment, the metal foot 28 of the tank 12is located in the internal channel 46 formed in the header 14.Thereafter, the crimping tabs 44 are folded around the foot 28 such thatthey contact its upper surface 30. This assures proper contact andalignment of the components prior to sealing. The assembly, is thenpreferably sealed, such as through brazing. As discussed above, avariety of other sealing processes may be utilized. Moreover, a varietyof methods for crimping the metal tank 12 and the header 14 may also beutilized. It should be understood that a sealant, such as a gasket 50,may be located between the lower surface 32 of the tank foot 28 and theinternal channel 46.

[0029]FIG. 7 illustrates another method for attaching the metal tank 12to the header 14. In FIG. 7, the metal foot 28 of the tank 12 is locatedin the internal channel 46 formed in the header 14. Thereafter, theconnection is sealed by positioning the spacer 52 on the upper surface30 of the foot 28 around the entire perimeter of the foot 28. After thespacer 52 has been positioned, the crimping tabs 44 are then foldedaround the foot 28 to contact the spacer 52. This configuration alsoassures proper contact and alignment of the components prior to sealingand is an alternative to brazing. Again, various methods for crimping aswell as various sealing methods may be utilized. Each of the methodsalong with the preferred design allows current radiator core headers tobe quickly and efficiently integrated with current manufacturingprocesses, thereby producing a rapid and cost effective transition.

[0030] The sealing process may be accomplished by a variety of knownjoining methods, such as using a gasket, adhesive, soldering, or brazingwith a variety of binders, including single or multi-cladded materialsand/or pastes. The heat exchanger 10 preferably utilizes a stampedaluminum tank, which is crimped to an aluminum radiator core. Theassembled heat exchanger is then preferably brazed. It should beunderstood that for some applications, the core could be brazed first,prior to crimping the tank to the core, thereafter the entire assemblycould be brazed. Alternatively, in other applications, the tank could becrimped to a non-brazed core initially, followed by brazing the entireassembly. Additionally, brazing of the tank may also require a varietyof single or multi-cladded materials or the use of brazing powders orpastes, depending upon the application, as would be understood by one ofskill in the art. Additionally, in another application, the tank can bemade from a stamped brass, which would then be crimped to a copper andbrass core and then soldered. Further, in yet another application, astamped brass tank is crimped to a copper and brass core and thenbrazed.

[0031] In accordance with the preferred embodiments described above, thecomponents such as filler necks, connectors, and brackets would befabricated as separate pieces and then joined to the tank. This requiresadditional labor than an injection molded tank, however, the costdifference is likely nominal. The present invention provides significantadvantages, however, by providing a significantly more durable productwhich minimizes in-service failures at the connectors due to cracking,minimizes in-service failures due to leaking gaskets, reduces theoverall leak rate in the manufacturing process, and reduces the overallcost. Further, the disclosed invention, provides an environmentaladvantage by utilizing either an all aluminum or all copper and brassconstruction (homogenous materials), which simplifies and eases theability to recycle the respective heat exchanger and therefore furtherreduces the cost.

[0032] While preferred embodiments of the invention have been describedhere and above, those of ordinary skill in the art will recognize thatthese embodiments may be modified and altered without departing from thecentral spirit and scope of the invention. Thus, the embodimentsdescribed here and above are to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims, rather than by the foregoingdescriptions, and all changes which come within the meaning and range ofequivalency of the claims are intended to be embraced herein.

What is claimed is:
 1. A heat exchanger comprising: a metal tank havingan upper portion and a lower portion; an integral foot formed around aperiphery of said lower portion of said metal tank; said integral foothaving an upper surface and a lower surface; and a header having aplurality of crimping tabs formed about its periphery, each of saidplurality of crimping tabs foldable so as to lie above and generallyparallel to said upper surface of said integral foot to retain saidmetal tank.
 2. The heat exchanger as recited in claim 1, wherein one ormore of said plurality of crimping tabs contact said upper surface ofsaid integral foot to retain said metal tank in position with respect tosaid header.
 3. The heat exchanger as recited in claim 1, furthercomprising: a spacer disposed between said upper surface of saidintegral foot and an underside of said crimping tabs.
 4. The heatexchanger as recited in claim 2, wherein the heat exchanger is brazed toprovide a leak-free connection between said foot and said crimping tabs.5. The heat exchanger as recited in claim 1, wherein said header has aninternal channel formed therein adjacent its periphery for receipt ofsaid integral foot therein.
 6. The heat exchanger as recited in claim 8,further comprising a sealant disposed between said lower surface of saidintegral foot and said internal channel.
 7. The heat exchanger asrecited in claim 1, wherein said metal tank is comprised of a stampedaluminum material.
 8. The heat exchanger as recited in claim 1, whereinsaid header is comprised of an aluminum material.
 9. A method of forminga heat exchanger comprising: forming a metal end tank with an integralfoot portion, said foot portion having an upper surface and a lowersurface; forming a header with a plurality of crimping tabs; locatingsaid metal end tank in said header; folding said crimping tabs aroundsaid integral foot portion to secure said metal end tank to said header;and joining said crimping tabs to said integral foot portion.
 10. Themethod of claim 9, wherein step of sealing includes brazing the heatexchanger.
 11. The method of claim 9, wherein said crimping tabsdirectly contact said upper surface of said integral foot portion. 12.The method of claim 9, further comprising: inserting a spacer betweensaid upper surface of said foot portion and an underside of saidcrimping tabs.
 13. The method of claim 9, wherein said step of formingcomprises stamping said metal end tank from an aluminum material. 14.The method of claim 9, further comprising: forming an internal channelin said header which is intended to receive said foot portion therein.15. The method of claim 14, further comprising: locating a sealantbetween said lower surface of said foot portion and said internalchannel.
 16. A heat exchanger comprising: a metal tank having anintegral foot portion disposed about aT least a portion of the peripherythereof; a header having a plurality of crimping tabs for engagementwith said foot portion, said header having a channel formed therein forreceipt of said foot portion.
 17. The heat exchanger of claim 16,further comprising a spacer disposed between an upper surface of saidintegral foot and an undersurface of said crimping tabs.
 18. The heatexchanger of claim 16, wherein an underside of said crimping tabscontacts an upper surface of said integral foot.
 19. The heat exchangerof claim 16, wherein the heat exchanger is brazed to provide a leak-freeconnection between said foot and said crimping tabs.
 20. The heatexchanger of claim 16, wherein said metal tank is comprised of a stampedaluminum material.